Unlock your smartphone with a digital tattoo

A TEMPORARY 'digital tattoo' that lets wearers unlock their smartphones without having to punch in a code has gone on sale for $10 in the US.

Created to work exclusively with Motorola's Moto X smartphone, the small circular patch uses near field communications technology (NFC) to talk to mobile device and lasts for five days once stuck to the user's skin.

The technology behind the tattoo was originally developed by Google's ATAP research and development team (otherwise known as the Advanced Technology and Projects group - they're currently make 3D-capable and modular smartphones) and the patches are currently being sold at $10 for a pack of five.

"An average user unlocks their phone 39 times a day and it takes them 2.3 seconds every time they do so," says Google's Deepak Chandra in a promotional video. "It is so cumbersome that more than 50 per cent of users do not lock their phones, exposing their personal data to theft."

Chandra and his fellows obviously think an easy way round this is to make everyone spend $10 on electronic tattoos every month - although the company previously developed a NFC clothes clip that does the same job without needed to be replaced (unless you leave it in the wash).

The idea of a 'digital tattoo' sounds exotic, but developments in flexible electronics are making this an increasingly common product category - Motorola even patented a similar patch which offers a built-in microphone last year.